Theres a machine toward the end of the game, after you've collected all of the ingredients for Agrippa, and the Shadow grows throughout the area.

Theres an area to the left of the 4 way bridge that has a machine with gears that you can break by jamming a large rock in it (at least what i used for it)

What was this machines purpose? i went there before completing the potion in the lab, and just assumed i had to break it XD I dont know what the significance was to breaking this machine, as i had no memento about it.

I guess, machine "feeds" the barrier. Orb would try to "suck" the energy, but with machine feeding it it will go on forever. When you disable machine, barrier has some energy left working. And orb disables it. Like static electricity discharge